I doubt that it will be used but maybe in the far future someone will if ever :) (Sth like war factions in Skyrim, assaulting Dagoth fortress etc.)
1. Redoran house
a. Hwacha
b Catapult
c Heavy archers
2. Hlaalu
a. Sapping point
b. Siege tower
c. Battering ram
Most Redoran's stuff will be not animated. Maybe only launching. To save time and avoid problems missiles will fire high into sky, then you don't care about trajectory. To show what I imagine how it's work I give this video. U will get several arrows. Each type to each attack (Heavy archers, Hwacha, Catapult).
Heavy archers - 10-15 attacks - many arrows with quite small damage, big area, good for many week enemies.
Hwacha - 5-10 attacks - medium amount of missiles, medium area, good for average enemies.
Catapult 4-6 attacks - one missile, small area, good for really tough guys, huge amount of damage.
Hlaalu will be more direct contact. As animating movement of the same sieges will be quite easy, worst part will be animating destruction. And of course battlefield needs plain terrain.
I'm aware it's very likely it will be reject but maybe some day some daredevil will do it :)